The present invention relates to an optical head and an apparatus for recording and reproducing optical information through the use of the optical head.
As a system of reducing an optical head mounted in an apparatus for recording and reproducing optical information on and from an optical medium like an optical disk, several prior arts have been made public as disclosed in JP-A-62-58432, JP-A-64-46242, JP-A-4-255923, and JP-A-6-251410. The optical head disclosed in the publication of JP-A-62-58432 is arranged so that photo detector elements and a semiconductor laser having a Fabri-Perot horizontal resonator as a light source are integrated on the same substrate. On the other hand, the optical head disclosed in JP-A-64-46242, JP-A-4-255923, or JP-A-6-251410 employs the so-called surface emitting laser as its light source.
For the optical head disclosed in JP-A-62-58432, in order to apply the optical head to the apparatus for recording and reproducing optical information such as an optical disk drive, it is necessary to curve an optical axis of a light flux fired from a semiconductor laser by 90 degrees. The publication of JP-A-62-58432 has disclosed a method of forming a reflective mirror through the use of an etching technique, for example. However, this method burdens the manufacturing process with great difficulty. Further, since the semiconductor laser needs a different density of impurities to be implanted from the photo detector elements, if both of the semiconductor laser and the photo detector elements are formed by the same process, disadvantageously, it is difficult to obtain the sufficient characteristics of both.
If the surface emitting laser is used as a light source like the optical head disclosed in JP-A-64-46242, JP-A-4-255923, or JP-A-6-251410, no reflective mirror is required to be formed unlike the optical head disclosed in JP-A-62-58432. Hence, the use of the surface emitting laser as the light source makes the manufacturing process a bit simpler. However, at this time, the difficulty of the surface emitting laser in enhancing an output power and fixing a direction of polarization of outgoing light makes it difficult to apply such an optical laser to apply to an apparatus for recording and reproducing recordable optical information.